Chore: Move identity and errutil to apimachinery module (#89116)

pkg/apimachinery/errutil/errors_example_test.go

@@ -0,0 +1,60 @@
+package errutil_test
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"path"
+	"strings"
+
+	"github.com/grafana/grafana/pkg/apimachinery/errutil"
+)
+
+var (
+	// define the set of errors which should be presented using the
+	// same error message for the frontend statically within the
+	// package.
+
+	errAbsPath     = errutil.BadRequest("shorturl.absolutePath")
+	errInvalidPath = errutil.BadRequest("shorturl.invalidPath")
+	errUnexpected  = errutil.Internal("shorturl.unexpected")
+)
+
+func Example() {
+	var e errutil.Error
+
+	_, err := CreateShortURL("abc/../def")
+	errors.As(err, &e)
+	fmt.Println(e.Reason.Status().HTTPStatus(), e.MessageID)
+	fmt.Println(e.Error())
+
+	// Output:
+	// 400 shorturl.invalidPath
+	// [shorturl.invalidPath] path mustn't contain '..': 'abc/../def'
+}
+
+// CreateShortURL runs a few validations and returns
+// 'https://example.org/s/tretton' if they all pass. It's not a very
+// useful function, but it shows errors in a semi-realistic function.
+func CreateShortURL(longURL string) (string, error) {
+	if path.IsAbs(longURL) {
+		return "", errAbsPath.Errorf("unexpected absolute path")
+	}
+	if strings.Contains(longURL, "../") {
+		return "", errInvalidPath.Errorf("path mustn't contain '..': '%s'", longURL)
+	}
+	if strings.Contains(longURL, "@") {
+		return "", errInvalidPath.Errorf("cannot shorten email addresses")
+	}
+
+	shortURL, err := createShortURL(context.Background(), longURL)
+	if err != nil {
+		return "", errUnexpected.Errorf("failed to create short URL: %w", err)
+	}
+
+	return shortURL, nil
+}
+
+func createShortURL(_ context.Context, _ string) (string, error) {
+	return "https://example.org/s/tretton", nil
+}